1. Field
The disclosure relates to the field of network security, and in particular, to updating a cache for storing security records.
2. Background Information
Digital information processing devices such as computers, routers, switches, network appliances, set-top boxes, and the like, which perform security related tasks may include hardware offloading devices (“HODs”) to perform at least some of the security related tasks. HODs generally can reside either on a network device or as a separate device on a host. One advantage of such an architecture may be to reduce the processing burden on other resources. Also, a particular hardware offloading device may be designed to do certain tasks more efficiently.
The performance of some security related tasks may involve a security record. A security record is a data structure which includes information that may be useful in performing certain security related tasks. For example, the IPSEC protocol (defined as of 2003 in IETF RFC1825 and RFC2401, et al., but continually evolving), uses security associations (SAs). A security association (SA) is a set of security parameters that determines at least in part which transformation is to be applied to an IPSEC packet and how it should be applied. For example, a SA may include a cryptographic key useful for performing encryption, decryption and/or authentication.
In some cases, a hardware offloading device may be less efficient unless a security record is located on or near the hardware, for example, in a hardware table. The term “cache” will be used in this patent to refer to such storage that may be located on or near the hardware. That is, if the security record is not located in the cache, the hardware offloading device may have to wait for the security record to be transferred from some other location, which may introduce a significant or unacceptable amount of delay. When the requested security record is on the hardware, it is called a “hit”, and when it is not, it is called a “miss”.
It may be desirable to have as many hits as possible. Moreover, it may be that the hardware table is of limited size. If so, then the efficiency of the hardware offload device may depend at least in part on which security records are actually stored in the hardware table. That is, the number of hits may depend on the method used to determine which security records will be stored in the hardware table. An improved process for determining which security records are stored on the hardware table may result in an improvement in the number of hits versus misses.
Thus, there is a need for an improved method of, and corresponding apparatus for, determining which security records are stored on or near a hardware offloading device.